McIlvanney set Laidlaw in the specific social situation in Britain in the mid- to late- nineteen seventies: the publishing year is 1977. The clip seen from Johnny Rotten's video autobiography of the Sex Pistols, The Filth & the Fury, shows the deteriorated condition of Britain -- as Laidlaw describes the cities, "....Just architectural dumps where they unloaded the people like slurry."
This was the state of life in the U.K. that gave rise to both Punk Rock and Thatcherism. John Lydon (aka Johnny Rotten) makes this point directly in "The Filth & the Fury," showing the first image of Margaret Thatcher with the voice-over, "People had had enough." (Lydon's point in the opening sequence is his statement that "the Labour Party, which had promised so much after the War, had done so little for the working class," over clips of Heath & Wilson successively.)
This has to be kept clear for any useful understanding of modern British literary history (i.e. my specialty!). Punk Rock was not a response to Thatcher: they were both responses to the same social condition -- neither Punk nor Thatcherism would have existed without the state of affairs in Britain that conceived them both. The chronology makes Rotten's point more clearly -- especially for North Americans & those who were not there (as, ahem, I was ....)
Margaret Thatcher came to power in the middle -- May -- of 1979. Laidlaw was published in 1977, & presumably written in 1976. Punk Rock was effectively finished by 1979. (It softened into New Wave. What is marketed as 'Punk' today is smooth up-tempo pop.) Here's Johnny Rotten from No Irish, No Blacks, No Dogs:
By 1978 the masses of Great Britain had woke up to “Punk”, but it had become a tired cliche for third rate pub bands and chancers.We do the facts here, and analyse the literature accordingly.
(ps: From the landscape in Laidlaw, I'm taking that Punk reached Scotland at about a eight- to twelve- month lag from London.)